This is a multicenter double-blind placebo controlled study on the ability of hyperimmune intravenous immune globulin to prevent vertical transmission of HIV from HIV+ mothers to their offspring. Four hundred mothers nationwide are selected for study who have a high rate of transmission because their illness is sufficiently advanced that they are require ZDV as part of their own care. If the mother agrees to participate, ZDV will be continuedduring her pregnancy, and she will be given an intrapartum dose of ZDV, and her infant will receive oral ZDV for 6 weeks.